The present invention relates to cleaning and more particularly to a composition and a process for cleaning optics and highly-polished metal surfaces.
The art is replete with cleaning compositions and processes for a wide variety of objects. For example, U.S. Pat. No. 3,957,531 to Tipping et al is concerned with a cleaning process utilizing, in one embodiment, a trichlorotrifluoroethane capable of forming an azeotrope with isopropyl alcohol as a first cleaning mixture. A second cleaning mixture designated as a rinse may contain as much or less alcohol by weight. It is apparently essential that both the first and the second cleaning mixtures comprise the same materials and be capable of forming an azeotrope. The cleaning mixture may also contain other solvents or additives including cationic, anionic and non-ionic detergents. The mixtures are disclosed as being utilized for cleaning printed circuit boards with no mention being made of application thereof to optical components or highly polished metal surfaces.
In another patent to Tipping et al, U.S. Pat. No. 3,904,430, the compositions disclosed are specifically identified as being non-azeotropic. Additionally, while the mixtures may contain trichlorotrifluoroethane, the use of isopropyl alcohol is specifically excluded. The compositions do contain auxiliary solvents, however, among these being 2-ethoxyethanol. As in the other Tipping et al disclosure mentioned above, the compositions are intended for cleaning printed circuit boards and can contain other solvents or additives.
In U.S. Pat. No. 3,340,199 to Clay et al, there is disclosed an azeotropic composition comprising trichlorotrifluoroethane, isopropyl alcohol and possibly, a surface active agent. The composition is disclosed as being useful in the cleaning of a variety of articles of metal, glass or plastic including optical components. The composition is, however, a one-step cleaner of the type which are known to leave noticable amounts of residue on the surfaces after cleaning.
In U.S. Pat. No. 3,903,012 to Brandreth, there is disclosed a water displacement composition which may contain trichlorotrifluoroethane and possibly isopropanol, as well as members selected from one or more groups of a variety of surfactants. Where any residue from the disclosed treatment remains on the non-shiny materials treated, it can be subsequently removed by dipping or spraying the article in pure solvent, such as pure trichlorotrifluoroethane. This is not disclosed as a cleaning composition suitable for cleaning optics or polished metal.
In U.S. Pat. No. 3,728,269 to Stephenson et al there is disclosed a volatile cleaning composition which may be sprayed from an aerosol can onto an article to be cleaned, for example an optical component, and requires no rubbing or wiping of the surface. The composition simply runs off the surface and evaporates. While the compositions are disclosed as including isopropyl alcohol as well as alkoxy alcohols, there is no mention of trichlorotrifluoroethane or of a second cleaning step or composition.
With all the prior art references dealing with cleaning compositions broadly and for specific purposes, there is yet a need for a cleaning composition and method which are capable of effectively and efficiently cleaning highly-polished surfaces, such as those employed in optics and highly-polished metal surfaces, without the need for rubbing which could damage the surfaces but yet which leave the surfaces free from any significant residue.